The Surveillance is a continuing series of comparable annual surveys of drug use (1968-1973) among junior and senior high school students in San Mateo County, California. The surveys were administered to students in public and private and parochial schools. Levels of use of alcoholic beverages, amphetamines, LDS, barbiturates, marijuana, tobacco and heroin were queried. Significant differences in use levels have been shown between sexes, grades and years. Comparability between surveys is stressed, making it possible to trace levels of use through the population over time, which could make a contribution toward setting up a general epidemic model with important implications for long-range strategies for control. Data which has been reduced to compatible machine readable form will be used for more elaborate analyses in the near future. The survey is noteworthy for its low per capita cost.